Field of Invention
The invention relates to a method for sterilizing parisons consisting of a thermoplastic material that are provided for the manufacture of blow-molded containers in which a sterilization agent is introduced by an applicator into an inner space of the parison.
Furthermore, the invention relates to a device for sterilizing parisons consisting of a thermoplastic material that are provided for the manufacture of blow-molded containers, whereby a supply device for loading an inner space of the parison with a sterilization agent comprises at least one applicator that can be transported at least in sections together with the parison.
The invention also relates to a method for the blow-molding of containers that comprises at least one blow station, arranged on a carrier structure, for transforming thermoplastic parisons into the containers, whereby a sterilization device is arranged in a transport direction of the parisons in front of the blow station.
Brief Description of Related Art
A manufacture of sterile, blow-molded containers typically takes place in such a manner that these containers are sterilized using hydrogen peroxide or other chemicals after their blow-molding and before being filled. The sterilization of the parisons used in the blow-molding of the containers as finished product, in particular the area of the inner surface of these parisons, is also known.
In a container molding by the action of blowing pressure, parisons consisting of a thermoplastic material, for example, parisons consisting of PET (polyethylene terephthalate) are supplied inside a blow-molding machine to different processing stations. Such a blow-molding machine typically comprises a heating device as well as a blowing device in whose range the previously tempered parison is expanded by biaxial orientation to a container. The expansion takes place with compressed air that is introduced into the parison to be expanded. The technical course of the method in such an expansion of the parison is explained in DE-OS 43 40 291.
The basic construction of a blow station for the container molding is described in DE-OS 42 12 583. Possibilities for tempering the parisons are explained in DE-OS 23 52 926.
Inside the device for the blow-molding the parisons and the blown containers can be transported with the aid of various handling devices. In particular, the use of transport mandrels onto which the parisons are mounted has proven itself. However, the parisons can also be handled with other carrying devices. The use of gripping devices for handling parisons and the use of spreading mandrels that can be introduced into a mouth area of the parison for holding it also belong to the available constructions.
A handling of containers using transfer wheels is described, for example, in DE-OS 199 06 438 in an arrangement of the transfer wheel between a blow wheel and output section.
The already explained handling of the parisons takes place on the one hand in the so-called two-stage methods in which the parisons are at first produced in an injection-molding method, subsequently intermediately stored and only later conditioned as regards their temperature and inflated to a container. On the other hand, there is a usage in the so-called one-stage methods in which the parisons are suitably tempered immediately after their injection-molding manufacture and a sufficient solidification and subsequently inflated.
As regards the blow stations used, various embodiments are known. In blow stations arranged on rotating transport wheels a book-like ability of the mold carriers to fold out is frequently found. However, it is also possible to use mold carriers that can shift relative to each other or that are guided in a different manner. In the case of stationary blow stations, that are in particular suited for receiving several cavities for container molding, plates typically arranged parallel to each other are used as mold carriers.
As regards the sterilization of parisons, various methods and devices are already known from the prior art that, however, all exhibit disadvantages specific to their methods and that oppose a reliable sterilization of the parisons at high throughput rates at the same time.
For example, in EP-A 1 086 019 the sterilization of hot parisons with a hot, gaseous sterilization agent is described. Separate treatment stations arranged in sequence are used, namely, a first heating module, a sterilization module and a second heating module. The disadvantage here is the temperature behavior of the parison during the sterilization procedure and the uncontrolled exiting of the sterilization agent from the parison during the heating.
EP-A 1 896 245 describes a method in which prior to the heating a gaseous sterilization agent is introduced into a cold parison and condensed there. The ensuring of a complete formation of condensate on the entire inside surface of the parison is problematic here since the incoming, hot sterilization agent raises the temperature of the inner wall of the parison. Furthermore, the sterilization agent also exits from the parison here after its evaporation in the area of the heating in an uncontrolled manner during the heating.
EP-A 2 138 298 describes a device in which the sterilization devices are arranged by way of precaution in front of the blowing module used as well as behind the blowing module used. This results in a very great expense for machine construction.
WO 2010/020530 A1 describes the arrangement of a sterilization device between a heating device and the blowing module. In this method the charged amount of sterilization agent into the area of the blowing module can be predicted only with difficulty. Moreover, the amount of sterilization agent discharged into the environment cannot be controlled and a corresponding contamination is not excluded.
In general the attempt is made to avoid an uncontrolled propagation of the sterilization agent in the heating area as well as in the area of the blowing module since the sterilization agents used frequently have corroding properties. Thus, the greater a discharged amount of sterilization agent is, the higher the expense for machine construction for avoiding corrosion damage, for example, by the use of especially corrosion-resistant materials that are therefore more expensive.
On the other hand, the attempt is made to carry out the sterilization in the shortest possible process time and to minimize the expense for the machine construction for constructively realizing the sterilization device.
The present invention has the problem of improving a method of the initially cited type in such a manner that a reliable sterilization can be carried out in a simple manner.